1. Field of the Invention
The present invention is a retractable USB memory stick and more particularly, to such a retractable USB memory stick that utilizes a seamless flat tube for the metal casing.
2. Description of the Related Art
USB memory stick is a mobile data storage device connectable to a computer for data access and convenient for carrying. Following fast development of technology, the storage capacity and application range of USB memory stick have been greatly improved.
Retractable USB memory sticks are commercially available. A regular retractable USB memory stick comprises a PC board having a USB interface circuit and a memory IC package, an insulative PC board holder holding the PC board, and a housing formed of two insulative half shells for accommodating the insulative PC board holder. The insulative PC board holder has a push member extended out of the housing and operable to move the USB interface circuit in and out of the housing.
U.S. Pat. No. 6,932,629 discloses a retractable USB memory stick design entitled “Device with USB terminal” in which device main body with a USB terminal and a cap including a housing space for housing at least the USB terminal are provided. The device main body and the cap are assembled so that they can be moved in an extending or compressing manner relative to each other by inserting at least the USB terminal to the housing space, or can be rotated relative to each other in an extended state without removing the cap from the device main body.
U.S. Pat. Nos. 6,979,210 and 7,462,044 disclose a retractable USB memory stick design, entitled “Thumb drive with retractable USB connector”. According to this design, the thumb drive has a memory, a male USB connector coupled to the memory for connecting to a USB port of a computer appliance, and an extension/retraction mechanism coupled to the connector and memory for extending the connector from an enclosure of the drive and for retracting the connector when not in use.
Further, US application publication Number US 2008/0233776 A1, entitled “Retractable memory drive” discloses a retractable memory device having a top shell member, an intermediate carrier means, an electronic device, for example, USB thumb drive and a bottom shell member, i.e., the top shell member and bottom shell member constitute a housing.
FIG. 20 shows a simple design of retractable USB memory drive according to the prior art. According to this design, the retractable USB memory drive comprises an outer shell 91 defining a sliding way 92, a circuit board 93 slidably received in the sliding way 92 of the outer shell 91. The circuit board 93 has a T-shaped sliding block 94 selectively engageable into a first locating hole 911 or second locating hole 912 in the sliding way 92 to lock the circuit board 93 to the outer shell 91 in the extended or received position. This retractable USB memory drive structure is easy to assemble when compared to the prior art design in which the outer shell is formed of a top shell member and a bottom shell member, however this retractable USB memory drive structure has no means to stop the circuit board 93 in the outer shell 91. Thus, the circuit board 93 may fall out of the outer shell 91 accidentally.
Further, the aforesaid various prior art designs have a common drawback of inconvenient and time-consuming assembly process, resulting in an increased manufacturing cost. Therefore, improvements are required.